<!DOCTYPE html>
<title>ViewTransitionTypeSet should not crash when documentElement is null</title>
<link rel="help" href="https://www.w3.org/TR/css-transitions-2/">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>

  test(() => {
    assert_implements(document.startViewTransition);

    const { types } = document.startViewTransition();
    document.documentElement.remove();
    types.add("a");
    assert_array_equals([...types], ["a"]);
  }, "ViewTransitionTypeSet should not crash when documentElement is null");
</script>

</html>
